Exogenous hydrogen sulphide promotes plant flowering through the Arabidopsis splicing factor AtU2AF65a.

Alternative splicing (AS) is an important regulatory mode at the post-transcriptional level, through which many flowering genes regulate floral transition by producing multiple transcripts, and splicing factors have essential roles in this process. Hydrogen sulphide (H 2 S) is a newly found gasotransmitter that has critical physiological roles in plants, and one of its potential modes of action is via persulfidation of target proteins at specific cysteine sites. Previously, it has been shown that both the splicing factor AtU2AF65a and H 2 S are involved in the regulation of plant flowering. This study found that, in Arabidopsis, the promoting effect of H 2 S on flowering was abolished in atu2af65a-4 mutants. Transcriptome analyses showed that when AtU2AF65a contained mutations, the regulatory function of H 2 S during the AS of many flowering genes (including SPA1, LUH, LUG and MAF3) was inhibited. The persulfidation assay showed that AtU2AF65a can be persulfidated by H 2 S, and the RNA immunoprecipitation data indicated that H 2 S could alter the binding affinity of AtU2AF65a to the precursor messenger RNA of the above-mentioned flowering genes. Overall, our results suggest that H 2 S may regulate the AS of flowering-related genes through persulfidation of splicing factor AtU2AF65a and thus lead to early flowering in plants.